Verification and Validation Diagram of a Control Rod Guide Tube on top of a hot box dome that has been gradually heating up. A hole was drilled here to increase fluid flow and increase cooling. It worked as expected for one reactor and partially worked in another.

Simple model Model as two concentric cylindrical tubes connected by 4 small holes. Two inlets at the bottom with different inlet speeds and one outlet at the top through the inner tube. To investigate the CFD a simple model of this was made in GAMBIT

Unsurprisingly the velocity was largest through the holes And the pressure was high in the outer tube and lower in the inner tube. My first simple mesh was tested in fluent to learn about using GAMBIT and fluent.

User Errors Test slight changes in dimensions Move back inlet condition Geometry Generation Change the meshing around important areas Grid Generation Test refinement of grid Model Selection and Application Run different turbulence models Application Uncertainties Investigate the influence of assumptions on target variables Numerical Errors Vary space and time discretisation and iteration number Areas to investigate reliability